Technical data

Device Support on OpenVMS Systems
7.6 CRCTX Routines Enhanced (Alpha Only)
• IOC$DEALLOC_CNT_RES
• IOC$LOAD_MAP
These routines have changed as follows:
If you call IOC$DEALLOC_CRCTX with a valid CRCTX status (CRCTX$V_
ITEM_VALID set to 1), the service returns a bad status. If the SYSBOOT
parameter SYSTEM_CHECK is set, the system will crash. This prevents users
from deallocating a CRCTX when they have valid resources that have not been
deallocated.
You must call IOC$ALLOC_CNT_RES with an invalid CRCTX status (CRCTX$V_
ITEM_VALID set to 0). If you call this routine with a valid status, OpenVMS
assumes that you will lose the resources mapped by this CRCTX. OpenVMS does
not allocate new resources and returns a bad status. If SYSTEM_CHECK is set,
the system will crash. IOC$ALLOC_CNT_RES sets the valid bit before it returns.
IOC$DEALLOC_CNT_RES must be called with a valid CRCTX (CRCTX$V_
ITEM_VALID set to 1). If you call IOC$DEALLOC_CNT_RES with an invalid
CRCTX, OpenVMS assumes that the other parameters are not valid, and returns
a bad status. If SYSTEM_CHECK is set, the system will crash. IOC$DEALLOC_
CNT_RES clears the valid bit before it returns.
IOC$LOAD_MAP must be called with a valid CRCTX. If it is called with
an invalid CRCTX (CRCTX$V_ITEM_VALID set to 0), it assumes that the
other parameters are also invalid, and returns a bad status. If the SYSBOOT
parameter SYSTEM_CHECK is set, the system will crash.
These improvements indicate to device support and privileged-code application
developers whether they need to deallocate scatter gather registers, which are
treated by OpenVMS as generic resources. If the CRCTX$V_ITEM_VALID bit is
set, IOC$DEALLOC_CNT_RES still needs to be called.
7.7 Device Driver MON Version Handling (Alpha Only)
V7.3
As of OpenVMS V7.3, when SYSTEM_CHECK is enabled, device driver images
with names of the form SYS$nnDRIVER_MON.EXE will be automatically loaded
by the system loader. If a corresponding _MON version does not exist, the system
will use the default image name: SYS$nnDRIVER.EXE.
7.8 New Values for Length Parameter in System Routines (Alpha
Only)
V7.1-2
The following system routines called by OpenVMS Alpha device drivers have new
values for the length parameter:
IOC$READ_PCI_CONFIG
IOC$WRITE_PCI_CONFIG
IOC$READ_IO
IOC$WRITE_IO
7–4 Device Support on OpenVMS Systems